Axillary Malignant Peripheral Nerve Sheath Tumor With Aggressive Clinical Course: A Case Report

AIM: Malignant peripheral nerve sheath tumor (MPNST) involvement of the axillary region is exceptionally uncommon and poses significant diagnostic and therapeutic challenges. CASE PRESENTATION: We report the case of a 41-year-old woman who presented with a left axillary mass initially detected during pregnancy. Imaging revealed a large axillary lesion closely associated with neurovascular structures. Histopathological and immunohistochemical analyses supported an MPNST diagnosis. Despite multimodal management, including partial surgical resection, combination chemotherapy with ifosfamide/doxorubicin-based regimens, radiotherapy, repeated surgical interventions, and reconstructive procedures, the disease demonstrated aggressive behavior with multiple local recurrences, nodal and cutaneous metastases, and an eventual mass in the gluteal region. RESULTS: MPNSTs account for 3–10% of soft tissue sarcomas and are frequently associated with poor outcomes, particularly in tumors larger than 5 cm, high-grade lesions, and those associated with neurofibromatosis type 1. Diagnosis relies on a combination of histopathology, immunohistochemistry, and advanced imaging modalities. Complete surgical resection with negative margins remains the only potentially curative treatment; however, this is often not feasible due to tumor location and extent. Radiotherapy may improve local control, while chemotherapy has limited efficacy in advanced disease. CONCLUSIONS: Axillary MPNST is an exceedingly rare entity with an aggressive clinical course and poor prognosis. This case highlights the challenges in management and underscores the need for early diagnosis, aggressive multimodal treatment, and the development of more effective systemic and targeted therapies.